National Geographic : 2017 May
JOEL SARTORE PHOTOGRAPHED THIS MALE WATTLED JACANA AT THE DALLAS WORLD AQUARIUM. What kind of dad stays home with the kids while their mother is out having sex? A wattled jacana dad—even when he knows that he’s being cuckolded and the offspring he’s minding may not be his. Several species of Jacana are among the animal world’s most extreme cases of sex-role reversal, says behavioral ecolo- gist Peter Wrege of Cornell University. An assertive female collects a harem of up to five smaller males. In the span of about a week, she lays four eggs in one male’s nest while continuing to mate openly with him and others—“as many as 65 matings for one clutch,” Wrege says. Even in monogamous bird species, a female may “sneak copulations else- where,” he says. But as Wrege and col- league Stephen Emlen observed during years of research in Panama, the wattled jacana female’s cuckoldry is both public and frequent. To see how that affects pa- ternity of offspring, they tracked dozens of birds’ mating and egg laying, took blood samples, and ran DNA tests. The researchers concluded that for a jacana male with a promiscuous partner, “the risk of raising unrelated young may be as high as 75 percent.” In other words: He’s seen her mating with others, yet for three months he incubates eggs and raises chicks unlikely to all be his. Why do the males do this? “Basically, they’re stuck,” Wrege says. Hunting for a less promiscuous female would take time better spent trying to sire eggs. This way, although they may end up with other males’ kids, they also achieve the bio- logical imperative of having their own. SHE MATES, HE INCUBATES By Patricia Edmonds | EXPLORE | BASIC INSTINCTS WATTLED JACANA HABITAT/RANGE Freshwater bodies in most of Central and South America CONSERVATION STATUS Least concern OTHER FACTS Jacana jacana is also called lily-trotter, be- cause outsize feet help it walk on floating plants.